can you decipher this script ?

Linux and Unix-Like SuSE
1 
ssh-add -t 30 >/dev/null 2>&1
LOGNAME=`whoami`
cp $HOME/.ssh/known_hosts $HOME/.ssh/known_hosts.org
grep -v localhost $HOME/.ssh/known_hosts.org > $HOME/.ssh/known_hosts

ssh -1 -f -l $LOGNAME -o "ForwardX11 yes" -o "StrictHostKeyChecking no" -L 6003:195.244.210.107:2222 ext-proxy-2 sleep 5 >/dev/null 2>&1
xterm -title GIBFDX -e ssh -1 -q -o "StrictHostKeyChecking no" -l fujitsu -p 6003 -L 8080:accessmngr.gibtelecom.lan:8080 localhost &

can anyone decipher the above script word for word if possible I know what certain bits do but it would be great if an expert could explain, sorry im new to scripting and will also check the newbie threads.

thanks in advance

2

Please mention what version of SuSE you have.
Please edit post #1 if I have guessed the line breaks incorrectly. The line containing "sleep 5" still looks unlikely unless it is just testing the ssh connection.

Sorry but I cannot help with the actual query but I'm trying to get the post clearer for other posters.

1 Like
3

10.0 (i586)

4

It's just a script to add a new 'user account' to an ssh infrastructure, and seems to rely on using the known_hosts config files (there's one on each side) as the 'authentication'.

Just lookup each command and it's options with 'man',
and read up on how ssh works. Easy stuff :wink:

The 'remote' 'sleep 5' command allows you to run/request a 'reverse' connection,
a.k.a. 'bounce' off the remote server.
Similar to what you would do with a reverse VNC connection, but the 'listening' side only runs for 5 seconds..

2 Likes
5

@unisoftdesign
I know nothing about SuSE Linux. This could change overnight if I get interested.

What is the reason for the script lines which remove "localhost" from the file pointed to by $HOME/.ssh/known_hosts.org ? Where does this file come from?

Does SuSE Linux bash Shell not set $LOGNAME ? It's a standard Environment Variable in unix.

@llcooljatt
Please post the bits you understand. Saves time for the other posters.

1 Like
6

Same here, I just focus on the (generic) SSH and grep syntax. Who knows what flavour of SSH the OP is on?

No line is being removed. A line is grepped out and copied onto the other system. The known_hosts files are part of an existing SSH infrastructure.

Good point, maybe his version of Suse is weird/proprietary/commercialised, or a predecessor has been cutting and pasting too much? Document and annotate, people!

1 Like
7

the first bit having read it is trying to add known_hosts to known_hosts.org i presume then looks for a comparison and looks for non-matching lines but what does it do with them?

I think im getting confused how it all ties in.

I understand most of the options listed apart from -q ?

also what is
"StrictHostKeyChecking no"
"ForwardX11 yes"

also the line:
-l fujitsu -p 6003 -L 8080:accessmngr.gibtelecom.lan:8080 localhost &

the -p 6003 is the local linux port? mapping to blind host address/port ?

and $HOME is the users home directory?

8

Just had tea and is thinking...

---------- Post updated at 12:57 PM ---------- Previous update was at 12:04 PM ----------

It's not really comparing, the grep command is used to stream/spool the whole known_hosts file, minus any lines that have "localhost" in them. My SSH config files never have that in there, so I can't really help any further on that.

So are we. Some known_hosts file has appeared on the user's account which has lines in it for "localhost", which get pruned out.

Check the local man pages. My local system does not have a -q or -Q option.

Normally, yes. We have no idea if the system you are working on has black voodoo on it :wink: